Dynamic Observation of Hydrogen Gas Release during Crack Propagation in Al-Zn-Mg Alloy

Keitaro Horikawa; Shunsuke Hokazono; Hidetoshi Kobayashi

doi:10.4028/www.scientific.net/MSF.783-786.168

Paper Titles

An Investigation into Double Oxide Film Defects in Aluminium Alloys
p.142

A Novel Process for Grain Refining and Semisolid Processing
p.148

Ultrasonic Degassing of Aluminum Alloys
p.155

Morphology of Si Phase in Al-Mg-Si-Cu Alloys with Excess Si Addition
p.161

Dynamic Observation of Hydrogen Gas Release during Crack Propagation in Al-Zn-Mg Alloy
p.168

Isothermal and Non-Isothermal Annealing of Cold-Rolled Al-Mn-Fe-Si Alloys with Different Microchemistry States
p.174

Effect of Heat Treatment Conditions and Small Addition of Cu on Occurrence of Serration in Al-Si Alloys
p.180

Separation of Pure Silicon from Al-Si Alloy Melts
p.186

The Evolution of Texture and Deformation Anisotropy at an Equal Channel Extruded Aluminum 1050 Alloy
p.192

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Dynamic Observation of Hydrogen Gas Release during Crack Propagation in Al-Zn-Mg Alloy

Abstract:

We have developed a new testing device, which is capable of detecting hydrogen gas evolution from the microstructural changes at the same timing. The device is composed of the tensile testing machine equipped with a high-speed microscope and two types of quadrupole mass spectrometers installed in the ultrahigh vacuum chamber. Sampling rate of microscopic observation is 2000 fps. Hydrogen or deuterium was pre-charged to the 7075 aluminum alloy by means of the slow strain rate deformation, together with the exposure under the humid air atmosphere. The hydrogen amount was measured by using a thermal desorption analysis in advance. As a result, it was revealed that hydrogen gas was evolved when the surface crack was generated around the notch root of the test specimen. SEM observation also showed that the initial crack is related to the propagation of grain boundary fracture around the notch root. When compared to the microstructure and the hydrogen gas evolution near the notch root, the hydrogen amount evolved at the grain boundary was estimated to be about 3.0×10^-7 mol/m².